1. Field of the Invention
The present invention relates to paper feed systems for photographic printers.
2. Description of the Prior Art
In commercial photographic processing operations, photographic printers record photographic images in edge-to-edge relationship on a continuous web of photosensitive print paper. In this type of photographic printer, the print paper web is typically advanced by a predetermined feed length during each operating cycle of the printer in order to advance the next unexposed portion of the print paper web to a printing aperture. High intensity light is passed through the photographic film and imaged on the image area of the photographic print paper defined by the printing aperture to expose the photographic emulsion layers of the paper and record a photograhic image.
In the Pako B/C-24XL printer, the paper feed system which controls the feeding of the print paper web consists of a motor-driven takeup spool which pulls the paper web from a supply reel. As the paper is pulled from the supply reel to the takeup spool, a feed metering idler roller is turned. An encoder senses movement of the feed metering idler roller and produces a pulse for each increment of rotation. The motor which drives the takeup spool can be controlled at either of two preset levels, a high speed level and a low speed level. The motor is initially operated at high speed during a first portion of each paper feed and then is switched to low speed for the remainder of the feed cycle. The purpose of the low speed operation is to improve feed accuracy; the take-up roll will have less momentum at the time the motor is stopped since it is moving at the low speed. The disadvantage of the low speed operation, however, is that it increases the time required to complete a paper feed cycle, and thus affects the overall operating production rate of the printer.